A method for siliconizing carbon materials was described by a working group of DLR (Deutsche Forschungsanstalt fur Luft- und Raumfahrt e.V. [German Research Institute for Air and Space Travel e.V.]), Stuttgart, Institut für Bauweisen- ünd Konstruktionsforschung [Institute for Construction and Design Research], in the VDI [Association of German Engineers] Materials Conference in Duisburg on Mar. 9-10, 1994. Carbon materials, reinforced with fibers that consist of carbon, were infiltrated therein with melted silicon in a so-called “liquid siliconization method,” By heat treatment, the elementary silicon ‘reacts with the carbon to form silicon carbide. Structural components and in particular friction elements for brake and clutch systems in automobiles can be produced from such materials.
Similar methods are described in, for example, EP 0 956 276, with the carbon workpieces that are to be siliconized and suitably bonded powdery silicon being heated together; the melted silicon penetrates the carbon workpieces and reacts at least partially with the carbon to form silicon carbide.
All known methods are, however, batch methods; in the past, only batch-type conversion of carbon materials into materials with a silicon carbide-containing matrix was possible. In this case, the furnaces in which the silicon is melted and in which the reaction of liquid silicon with carbon to form silicon carbide is performed must first be charged, heated up under inert gas atmosphere and optionally evacuated, cooled after the reaction to form silicon carbide at the necessary holding time, and unloaded. Such a method requires long heating and cooling times and is inefficient in terms of energy use.
The object is therefore to indicate a method with which a treatment, to be operated semi-continuously, of workpieces that optionally consist of fibers, preferably of carbon, reinforced porous carbon with liquid silicon with at least partial conversion to silicon carbide, is possible.